Power amplifiers can be used in various applications from stereo systems to industrial motor control. The general purpose of a power amplifier is to take an input signal and make a signal suitable for driving a load, such as a loudspeaker. The power amplifier accomplishes this by increasing the strength of the input signal, which is typically measured in Watts. In a solid state power amplifier, transistors are used to increase current and/or voltage of the input signal and, as a result, increase the strength of the signal.
Solid state power amplifiers also exist as digital power amplifiers. Digital amplifiers involve using transistors as switches rather than current and voltage regulators as an analog amplifier would. Because of their switching approach, digital amplifiers are generally more power efficient than their analog counterparts over a similar amplification range. However, by using a digital power amplifier, an amount of quantization error typically results from digital-to-analog conversion following amplification. It is therefore desirable to have a more efficient power amplifier that can combine some of the efficiency of a digital power amplifier with a similar level of performance, in terms of absence of quantization noise, to an analog power amplifier.